Apparatus for making electrical connections



April 29, 1969 COBAUGH 3,440,723

APPARATUS FOR MAKING ELECTRICAL CONNECTIONS Original Filed Nov. 12, 1964 Sheet of April 1969 R. F. COBAUGH 3,440,723

I APPARATUS FOR MAKING ELECTRICAL CONNECTIONS Original Filed Nov. 12, 1964 Sheet 2 of s April 29, 1969 I COBAUGH 3,440,723

APPARATUS FOR MAKING ELECTRICAL CONNECTIONS Original Filed Nov. 12, 1964 Sheet 3 of 3 United States Patent US. Cl. 29-628 3 Claims ABSTRACT OF THE DISCLOSURE Disclosure relates to known method of making clip-type electrical connection between insulated wire and terminal post in which wire is dragged by terminal clip over a man drel and onto the post. In present method, mandrel is provided with a cutting blade or edge extending parallel to the direction of movement of the clip so that as wire is dragged over blade or edge, axial slit is formed in wire insulation. In finished crimped connection, metallic strands of wire are exposed by the slit and are held against, and in electrical contact with the surface of the post by the terminal clip.

This application is a continuation of application Ser. No. 410,623, now abandoned, which is a division of application, Ser. No. 282,092, filed May 21, 1963, US. Patent 3,186,078, which, in turn, is a continuation-in-part of US. Patent 3,239,918.

This invention relates to methods of forming an electrical connection between a conductor and a terminal post.

In US. Patent 3,239,918, I disclose a method and apparatus for making electrical connections between a terminal post and an insulated wire by positioning a mandrel in alignment with the post and sliding an open-sided terminal clip over the mandrel and onto the post. The mandrel is provided with an opening extending transversely of the path of movement of the clip into which the end of the wire is inserted. In accordance with one embodiment of the invention of US. Patent 3,239,918, a groove is pro vided on the surface of the mandrel which has a cross sectional area which is substantially equal to the cross sectional area of the conducting core of the wire so that as the clip moves past the wire, the insulation of the wire is cut by the edges on each side of the groove. Thereafter, and upon further movement of the clip towards the terminal post, the conducting core of the wire is withdrawn from the severed section of insulation so that after the clip comes to rest on the terminal post, the stripped end of the wire is held against the surface of the post by the clip. US. Patent 3,239,918, discloses several additional embodiments in which the mandrel is not used and in which the wire insulation is stripped prior to making the electrical connection. The foregoing brief description of one embodiment of the invention of US. Patent 3,239,918, is presented only as background information to the description of the present invention which follows.

The present invention relates generally to a method in accordance with the general teachings of US. Patent 3,239,918, where stripping of the insulation cannot be carried out in accordance with the teachings of US, Patent 3,239,918, and/ or complete stripping of the insulation from the wire is not desired. The present invention is useable with most types of insulated wires and has particular utility where it is necessary to form an electrical connection between a terminal post and a wire of the type commonly known as tinsel wire since wire of this type is not amenable to conventional insulation stripping techniques.

It is accordingly an object of the invention to provide an improved method for forming electrical connections between insulated wires and terminal posts. It is a further object of the invention to provide a method for forming electrical connections which does not require stripping of the insulation from the wire. A further object of the invention is to provide a method for forming an electrical connection between a terminal post and a tinsel wire. A further object is to provide a method for forming electrical connections between a wire and a terminal post in which the conducting core of the wire is brought into contact with the post and the insulation of the wire surrounds and seals the connection.

These and other objects of the invention are achieved in a preferred embodiment in which the generally channelshaped connector clip is moved past a transversely extending wire and onto the terminal post with which the connection is to be made. During such movement of the clip, its leading end engages the wire and drags it relatively towards the terminal post. In a preferred embodiment, an insulation severing knife is provided on the path of movement of the wire and is so located that the end portion of the insulated wire moves relatively over and along the knife edge so that an axial slit is formed in the wire insulation. Thereafter, the wire is compressed by the clip against the surface of the terminal post in a manner such that the insulation is flattened and the axial slit becomes an elongated axial gap exposing the metallic core of the wire. In the finished crimped connection, the exposed conducting core of the wire is pressed against the surface of the post and the flattened and parted insulation is disposed around the core with the connector clip holding the insulation and the core against the post to establish the electrical contact.

In the drawing:

FIGURE 1 is a perspective view of the leading end portion of a tool which can be used in the practice of the invention.

FIGURE 2 is a fragmentary sectional view on an enlarged scale showing the tool mandrel positioned against a terminal post and showing the end of a wire positioned in the mandrel preparatory to movement of the clip past the wire and onto the post in accordance with the method of the present invention.

FIGURE 3 is a view taken along the lines 33 of FIG- URE 2.

FIGURE 4 is a view similar to FIGURE 2 but showing the positions of the parts when the clip has moved partially along its path of movement towards the post and after the clip has initially engaged the wire.

FIGURE 5 is a view taken along the lines 55 of FIGURE 4.

FIGURE 6 is a sectional side view showing the manner in which the clip holds the wire against the terminal post in the completed electrical connection.

FIGURE 7 is a view taken along the lines 77 of FIGURE 6.

FIGURE 8 is a perspective View showing a section of strip of end-to-end connected clips for making electrical connections in accordance with the invention.

FIGURE 9 is a side view of the tool for carrying out the invention.

FIGURE 10 is a perspective view of a short section of tinsel wire.

Referring first to FIGURE 8, one form of terminal clip C for making connections in accordance with the invention comprises a flat web 2 having sidewalls 4 extending from its longitudinal edges. The marginal edge portions of these sidewalls are curled inwardly towards each other and towards the underside of the web 2, the distance between the curled edges of the sidewalls and the underside of the web being such that the connector is adapted to embrace a terminal post 1 and to clamp or hold the conducting core 5 of a wire 3 against the sur- 3 face of the post as shown in FIGURES 6 and 7. Advantageously, the leading end of the web 4 is provided with an outwardly cupped recess 8 which functions as a strain relief and as an insulation support for the emergent sectiog of the wire which extends from the lower end of the we One form of apparatus which can be used for carrying out the method of the present invention comprises a hand tool (FIGURE 9) having a depending handle 10 and an air cylinder 12 on its upper side. The type of tool shown in FIGURE 9 contains mechanism for feeding connector clips in strip form from a reel or other suitable source, and for transferring the leading connector of the strip to a position in front of a plunger which is driven by the piston rod of air cylinder 12. This mechanism in this particular type of tool is fully disclosed in US. Patent 3,198,983, and need not be described in detail here. Accordingly, only the structure of the nose portion of the tool, shown in FIGURE 1, will be described in detail. The disclosed tool is provided with a pair of cover plates 14 which encase the mechanism which actuates the various transfer devices, terminal fitting devices, and the plunger which are described below.

Referring now to FIGURE 1, the disclosed form of tool comprises a frame plate 18 having a mandrel block 20 mounted on its upper lefthand end as viewed in the drawing. A T-shaped mandrel comprising a rib 22 and a head 24 is provided on the upper side of mandrel block 20. The thickness of the mandrel head 24 is such that the connector clip can be moved over this projection with a relatively snug sliding fit. The head 24 does not extend to the end of the block but terminates in an undercut surface 26 beyond which an arm 32 extends which is adapted to be positioned against the side of the terminal post 1. Plates 28 are secured to the mandrel block on each side and have inwardly bent resilient fingers 30 extending towards the sides of the arm 32 to assist the operator in holding the tool steadily against the end of the post. A recess 34 extends downwardly as viewed in the drawing through the head 24 of the projection and into the rib 22 thereof and opens into the righthand side of the head.

The terminal clips are pushed by means of a plunger 38 from a T-shaped projection 44 on the upper end of a transfer slide 42 over the T-shaped mandrel. In the disclosed embodiment this plunger has a recess in its leading end in which the terminal clip is nested during such movement. The clips are loaded onto projection 44 of transfer slide 42 when the transfer slide is in a lowered position and is in alignment with a strip of clips on a feed track generally indicated at 49. Lowering of the transfer slide 42 is accomplished by means of a lever 46 which is actuated by the piston rod of the piston cylinder as fully explained in the above-identified Floyd application. The strip of clips is fed leftwardly in FIGURE 1 to position the leading clip on the projection 44 on slide 42 by means of reciprocable block 50 having a feed finger thereon which engages the strip to push it leftwardly as viewed in the drawing.

It is advantageous to provide a spring finger 62 on the upper side of the tool to bear against the surface of the terminal post when the tool is positioned against its end and to assist in holding the tool in its proper position for application of the clip. In the disclosed embodiment this spring extends from a block 60 which straddles the path of reciprocation of the plunger and which is mounted on a block 61 secured to the frame plate.

It will be understood that the linkages between the piston-cylinder and the various mechanisms for actuating the transfer slide 42 and the terminal feed block 50 as well as the sequence in which these elements of the disclosed tool operate are explained fully in the above-mentioned US. Patent 3,198,983, and need not be described in further detail since the instant invention is directed to the projection 22, 24 on the anvil, the recess 34, and the manner in which the insulated wire is slit during usage of the tool as will now be described.

A groove 64 is provided on the upper surface of the head 24 of the T-shaped projection and slopes from a location adjacent the frontal end of the tool towards the recess 34. As it approaches the recess 34, this groove drops off abruptly as indicated at 68 and merges with the lefthand side of the recess to provide a gently curved transition surface. As shown best in FIGURE 3, a V- shaped rib 66 is provided on the floor of the recess 64 centrally between the two sides. The apex of this rib is advantageously sufficiently sharp to permit it to cut into the insulation sheath 3 of the wire when the wire is dragged through the groove as is described below.

In use, the parts will normally be in the position shown in FIGURE 1 with a terminal positioned on the projections 44 of the transfer slide 42. The tool is positioned against the terminal post 1 with the end of the post disposed against the undercut surface 26 of projection 22, 24 and with the finger 30 hearing against the sides of the post. The operator inserts the end of an insulated wire into the recess 34 and squeezes the trigger 13 to admit compressed air into the righthand side of the cylinder and to drive the plunger 38 leftwardly in the drawing. The plunger first moves over the upper end of the transfer slide 42 and pushes the connector clip from the transfer slide and onto the projection 22, 24 of the mandrel. As the clip moves over this projection and past the recess 34, its leading end engages the wire 3 and first compresses it in the groove 64 of the head 24 of the projection. As the clip moves relatively leftwardly, the insulated wire is compressed to an increasing extent within the roove 64 due to the slope of the floor of the groove so that the wire is deformed until it effectively fills the entire cross section of the groove (FIGURE 5). As a result of this compression of the wire, the insulation on the underside of the wire is forced against the cutting edge of the rib 66 which forms an axial slit in the insulation extending to the end of the wire.

As the clip C moves relatively past the groove 64 and onto the terminal post 1, it is forced to yield resiliently as shown at FIGURE 7 and the wire is contained between the web and the opposed surface of the clip, The relatively high force exerted on the wire causes it to be flattened and the insulation is parted along the slit formed by the cutting edge of the rib 66. This flattening of the wire coupled with the force exerted on it by the clip has the effect of forcing the conducting core 5 of the wire against the surface of the terminal post so that after the clip has come to reset, an electrical connection as shown in FIGURE 7 is achieved.

Preferably, the physical properties of the clip should be such that when it is in the condition shown in FIG- URE 7 it will be capable of following the wire insulation if some of the insulation should flow from between the web and the terminal post. In other words, it is desirable that the clip should function as a spring member capable of compensating for relaxation of insulation which would otherwise involve a lowering of the contact pressure between the wire and the terminal post.

The invention can be practiced with any type of insulated wire which can be slit by the action of the cutting edge of the rib 66, for example, any of the conventional plastic insulations such as Teflon (polytetrafluoroethylene), nylon or conventional fiber insulations. One advantage which applies to all types of insulation is that the area of physical contact between the terminal post and the wire is completely surrounded by tightly compressed insulation material which is resiliently urged by the connector clip against the wire and the surface of the terminal post. This feature of the invention provides a continuous seal surrounding the contact areas against adverse environments such as corrosive moistures or gases.

The invention has been found to be of particular utility where it is necessary to form a connection between a terminal post and a wire of the type commonly identified as tinsel wire. A wire of this type is shown in FIGURE comprising a plurality of extremely small ribbon like strands 70 each of which is helically wrapped around a continuous core of fibers 72, usually natural fibers such as cotton. The individual strands 70 are, in turn, covered by an inner insulation sheath 74 and an outer insulating sheath 76. In FIGURE 10, these insulating sheaths are shown as being of natural fibers although tinsel type wires are also manufactured with at least one plastic insulating sheath in surrounding relationship to the strands,

This type of wire is use where a highly flexible wire is required but has proved to be particularly troublesome when electrical connections must be made. It does not respond to conventional stripping techniques for the reason that the conducting core is made up of the helical ribbons surrounding the fibers 72 so that any attempt to cut the wire may result in severing of the strands. Tinsel wires can be connected to terminal posts in accordance with the principles of the present invention with relative ease since it is only necessary to sever the outer insulating sheaths 74, 76 by means of the cutting edge on the rib 66 While the wire is being drawn through the groove 64. The helical strands of the tinsel Wire will then be exposed and will be pressed against the surface of the terminal post as is shown in FIGURE '7.

While the above described apparatus includes a cutting edge for forming the axial slit in the insulating sheath 3 of the wire, it has been found that with some types of insulation this cutting edge is not required. Particularly, where the insulating sheath comprises a plastic material having a high notch sensitivity and which tends to split after being stretched, it is possible to form the slit by merely drawing the wire over the surface of the anvil while it is held in a flattened condition by the connector clip as described in my previous application Ser. No. 171,074. When the wire is flattened under these circumstances it is stretched on its underside to a degree such that the insulation parts on opposite sides, that is on the side adjacent to the web and on the side adjacent to the anvil. It will be apparent from FIGURE 5 that such parting of the insulation will be brought about for the reason that it is highly deformed on these sides but is not deformed on the diametrically opposed sides where it is not confined.

An important purpose of the groove 64 in the disclosed apparatus is to center the Wire with respect to the cutting edge 66 as the wire is pulled or dragged by the clip from the recess and over the surface of the mandrel In the disclosed apparatus, this groove has a relatively large cross sectional area adjacent to the recess as indicated in FIGURES 3 and 4. Obviously, this groove can therefore be relatively more shallow than in the apparatus shown and under some circumstances can be eliminated entirely if movement of the Wire over the cutting means is achieved in another manner. For example, several spaced apart cutting edges can be provided on the mandrel which would be so located that movement of the wire over at least one of these edges would be inevitable.

The method of the present invention does not require the apparatus shown above but can be practiced without the aid of apparatus of any type other than a knife blade, or its equivalent, disposed on the path of movement of the clip. For example, the mandrel is not always required as explained in application Ser. No. 171,074 and the clip can be moved directly against the wire and onto the post. In order to part the insulation in accordance with the present invention, it is merely necessary to position a knife blade, mounted on a suitable fixture, in a position such that the wire is dragged along the edge of the blade while it is being dragged onto the post.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is oflered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art:

What is claimed is:

1. The method of electrically connecting an insulated conductor to a terminal post by means of a terminal clip, said clip being telescopically movable onto said post, said method comprising the steps of: positioning a portion of said conductor with its axis extending transversely of the axis of said post, locating a cutting means between said conductor and said post with a cutting edge thereof extending parallel to the axis of said post, and moving said clip against said conductor and onto said post whereby, said clip drags said portion of said conductor over said cutting edge and the insulation of said conductor is axially slit to expose the metallic core of said conductor, and upon movement of said clip onto said post, said exposed core is dragged over a surface of said post, and said conductor is held against said post by said clip with said exposed core in electrical contact with said surface.

2. The method of making an electrical connection between an insulated wire and a terminal post comprising the steps of: positioning said wire with its axis extending transversely of the axis of said post, locating an open sided terminal clip in alignment with said terminal post and on the opposite side of said wire from said post, 10- cating a cutting means in alignment With said post and between said post and said wire, moving said clip axially past said wire thereby to drag said Wire over said cutting means and to produce an axial slit in the insulation of said wire, and moving said clip onto said terminal post thereby to flatten said wire against said post whereby an axial gap is formed in said insulation and the conducting core thereof is exposed, and pressed into engagement with said post.

3. The method of making an electrical connection between an insulated tinsel wire and an open-sided terminal post by means of a terminal clip adapted to relatively tightly embrace said post, said method comprising the steps of: positioning said clip in axial alignment with said post, positioning said wire between said post and said clip with the axis of said wire extending transversely of the common axis of said clip and post and past the plane of the open side of said clip, moving said clip relatively towards said post and past a cutting edge disposed between said clip and said post whereby, said clip drags said wire over said cutting edge and over the surface of said post thereby to slit the insulation of said wire and to compress and flatten said wire against said post, said slit being widened, and the conducting core of said wire being brought into electrical contact with said post.

References Cited UNITED STATES PATENTS 3,239,918 3/1966 Cobaugh 29-206 X 3,040,150 6/1962 Rueger 339- X 2,795,769 6/1957 Wells 339-76 2,780,794 2/1957 Cresson 339-276 2,181,576 11/1939 Chirelstein 29203 JOHN F. CAMPBELL, Primary Examiner.

J. L. CLINE, Assistant Examiner.

US. Cl. X.R. 

